Industrial ecology is one of a number of new fields of study, such as 'green chemistry' or 'ecological economics', that have deliberately reached across different disciplines in both name and substance. This raises a number of issues for the practitioner, including difficult questions of boundary and field content (when is something 'industrial ecology' and when is it a part of another dialogue?). Such issues are challenging enough. But industrial ecology raises even more complex questions, in particular the possibility that in some senses, industrial ecology is one of the first post-modern fields of study, in that, unlike most more traditional disciplines, it embodies not a single ontology, but a set of complex and, in some ways, mutually exclusive ontologies. How such multi-ontological fields can be conceptualised, and represented coherently through traditional institutional forms such as journals and societies, is not yet clear, but it is highly likely that the industrial ecology community as a whole will need to learn to do so.